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**                     Jiedi(China nanjing)Ltd.                               **
**	               创建：夏曹俊，此代码可用作为学习参考                       **
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#include "XVideoWidget.h"
#include <QDebug>
#include <QTimer>
//自动加双引号
#define GET_STR(x) #x
#define A_VER 3
#define T_VER 4

FILE *fp = NULL;

//顶点shader
const char *vString = GET_STR(
	attribute vec4 vertexIn;
	attribute vec2 textureIn;
	varying vec2 textureOut;
	void main(void)
	{
		gl_Position = vertexIn;
		textureOut = textureIn;
	}
);


//片元shader
const char *tString = GET_STR(
	varying vec2 textureOut;
	uniform sampler2D tex_y;
	uniform sampler2D tex_u;
	uniform sampler2D tex_v;
	void main(void)
	{
		vec3 yuv;
		vec3 rgb;
		yuv.x = texture2D(tex_y, textureOut).r;
		yuv.y = texture2D(tex_u, textureOut).r - 0.5;
		yuv.z = texture2D(tex_v, textureOut).r - 0.5;
		rgb = mat3(1.0, 1.0, 1.0,
			0.0, -0.39465, 2.03211,
			1.13983, -0.58060, 0.0) * yuv;
		gl_FragColor = vec4(rgb, 1.0);
	}

);



//准备yuv数据
// ffmpeg -i v1080.mp4 -t 10 -s 240x128 -pix_fmt yuv420p  out240x128.yuv
XVideoWidget::XVideoWidget(QWidget *parent)
	: QOpenGLWidget(parent)
{
}

XVideoWidget::~XVideoWidget()
{
}

//初始化opengl
void XVideoWidget::initializeGL()
{
	qDebug() << "initializeGL";
	
	//初始化opengl （QOpenGLFunctions继承）函数 
	initializeOpenGLFunctions();

	//program加载shader（顶点和片元）脚本
	//片元（像素）
	qDebug()<<program.addShaderFromSourceCode(QGLShader::Fragment, tString);
	//顶点shader
	qDebug() << program.addShaderFromSourceCode(QGLShader::Vertex, vString);

	//设置顶点坐标的变量
	program.bindAttributeLocation("vertexIn",A_VER);

	//设置材质坐标
	program.bindAttributeLocation("textureIn",T_VER);

	//编译shader
	qDebug() << "program.link() = " << program.link();

	qDebug() << "program.bind() = " << program.bind();

	//传递顶点和材质坐标
	//顶点
	static const GLfloat ver[] = {
		-1.0f,-1.0f,
		1.0f,-1.0f,
		-1.0f, 1.0f,
		1.0f,1.0f
	};

	//材质
	static const GLfloat tex[] = {
		0.0f, 1.0f,
		1.0f, 1.0f,
		0.0f, 0.0f,
		1.0f, 0.0f
	};

	//顶点
	glVertexAttribPointer(A_VER, 2, GL_FLOAT, 0, 0, ver);
	glEnableVertexAttribArray(A_VER);

	//材质
	glVertexAttribPointer(T_VER, 2, GL_FLOAT, 0, 0, tex);
	glEnableVertexAttribArray(T_VER);


	//从shader获取材质
	unis[0] = program.uniformLocation("tex_y");
	unis[1] = program.uniformLocation("tex_u");
	unis[2] = program.uniformLocation("tex_v");

	//创建材质
	glGenTextures(3, texs);

	//Y
	glBindTexture(GL_TEXTURE_2D, texs[0]);
	//放大过滤，线性插值   GL_NEAREST(效率高，但马赛克严重)
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	//创建材质显卡空间
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width, height, 0, GL_RED, GL_UNSIGNED_BYTE, 0);

	//U
	glBindTexture(GL_TEXTURE_2D, texs[1]);
	//放大过滤，线性插值
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	//创建材质显卡空间
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width/2, height / 2, 0, GL_RED, GL_UNSIGNED_BYTE, 0);

	//V
	glBindTexture(GL_TEXTURE_2D, texs[2]);
	//放大过滤，线性插值
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	//创建材质显卡空间
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, width / 2, height / 2, 0, GL_RED, GL_UNSIGNED_BYTE, 0);

	///分配材质内存空间
	datas[0] = new unsigned char[width*height];		//Y
	datas[1] = new unsigned char[width*height/4];	//U
	datas[2] = new unsigned char[width*height/4];	//V

	fp = fopen("out240x128.yuv","rb");
	if (!fp)
	{
		qDebug() << "out240x128.yuv file open failed!";
	}


	//启动定时器
	QTimer *ti = new QTimer(this);
	connect(ti, SIGNAL(timeout()), this, SLOT(update()));
	ti->start(40);
}

//刷新显示
void XVideoWidget::paintGL()
{
	if (feof(fp))
	{
		fseek(fp, 0, SEEK_SET);
	}
	fread(datas[0], 1, width*height, fp);
	fread(datas[1], 1, width*height/4, fp);
	fread(datas[2], 1, width*height/4, fp);

	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D, texs[0]); //0层绑定到Y材质
	//修改材质内容(复制内存内容)
	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RED, GL_UNSIGNED_BYTE, datas[0]);
	//与shader uni遍历关联
	glUniform1i(unis[0], 0);


	glActiveTexture(GL_TEXTURE0+1);
	glBindTexture(GL_TEXTURE_2D, texs[1]); //1层绑定到U材质
										   //修改材质内容(复制内存内容)
	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width/2, height / 2, GL_RED, GL_UNSIGNED_BYTE, datas[1]);
	//与shader uni遍历关联
	glUniform1i(unis[1],1);


	glActiveTexture(GL_TEXTURE0+2);
	glBindTexture(GL_TEXTURE_2D, texs[2]); //2层绑定到V材质
										   //修改材质内容(复制内存内容)
	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width / 2, height / 2, GL_RED, GL_UNSIGNED_BYTE, datas[2]);
	//与shader uni遍历关联
	glUniform1i(unis[2], 2);

	glDrawArrays(GL_TRIANGLE_STRIP,0,4);
	qDebug() << "paintGL";
}


// 窗口尺寸变化
void XVideoWidget::resizeGL(int width, int height)
{
	qDebug() << "resizeGL "<<width<<":"<<height;
}